1. Field of the Invention
The present invention relates to the field of respiratory therapy. In particular, the invention is a unique medical instrumentation combining a meter for measuring the peak ability for exhalation of a patient with the administration of inhalation therapy for the patient.
2. Prior Art
Peak flow meters for measuring the maximum rate at which air is forced from the lungs during exhalation are used by inhalation and respiratory therapists and physicians for monitoring a patient""s respiratory condition for diagnosing potential and/or existing breathing problems. The meter generally comprises an open ended cylinder, marked with a graduated scale along its length. The patient breaths into the open ended cylinder, through a mouth piece, the patient""s breath impinging against a biased diaphragm. The biased diaphragm is moved down the cylinder, along the scale thus indicating a rate at which breath is exhaled from the lungs. A nebulizer is a device often used by inhalation and respiratory therapists and physicians for administering vaporized medication to a patient, presenting vaporized medication to a patient through an aerosol chamber or vapor holding cylinder. Through a mouth piece, at an end of the vapor holding cylinder, a patient inhales vaporized medication. Peak flow meters and nebulizers are each well known and often used medical instrumentations. The U.S. Pat. No. 4,944,306, issued to Alvino, Jul. 31, 1990 teaches an improved, patient adjustable, viewable, exhalation flow rate metering device or spirometer, also called a peak flow meter. A vertical housing, open at its upper end, connects, at its lower end to an horizontal cylinder with a mouth piece at one end and an open end at the other end. The connection between the vertical housing and the cylinder is at a point between the mouth piece and the open end of the cylinder. The vertical housing supports a biased piston on a positioning rod. The biased piston is in full view of the patient exhaling into the mouth piece and cylinder. Exhaled breath from the patient forces the biased piston up the positioning rod. The patient watches the piston rise up the positioning rod as the patient blows into the mouth piece. U.S. Pat. No. 5,565,630, issued to Shene, Oct. 15, 1996 teaches an improved peak flow meter for measuring peak exhalation air flow of a patient. Breath is exhaled, from the mouth, through a mouth piece, into a hollow chamber containing a biased, movable member which moves along the hollow chamber in response to pressure. A series of vent holes are provided in the wall of the chamber, along the path of the biased member. The holes increase in diameter as the length of the path increases. A graduated scale is marked on the cylinder, along the path. The biased, movable member moves along the path and graduated scale in response to pressure of a person""s or patient""s breath exhaled into the mouth piece. The position of the biased, movable member, along the graduated scale, indicates a peak breath flow of a person""s exhalation.
Nebulizers which meter vaporized medication to a person, are well known in the medical field. Examples of United States issued patents are:
The U.S. patent to F. M. Bird et al, U.S. Pat. No. 3,353,536 teaches a nebulizer which is essentially a fixed or stable unit and can be used for long term use. A relatively large container supports a large amount of liquid medication. Air, flowed into a large quantity of liquid medication, vaporizing the liquid which, in vapor form is presented to the patient for inhalation. The unit is designed for long term therapy where oxygen or air is administered to a patient. The U.S. Pat. No. 4,470,412, issued to Nowacki et al, teaches an inhalation valve for an antiasthmatic medication cartridge assembly. A pressurized cannister or cartridge containing a suitable medication for inhalation is used for dispensing high velocity bursts of a pressurized medicated inhalant, in vaporized form, into a sealed chamber. One end of the chamber is sealed by a slit diaphragm valve with an open mouth piece on the output side of the split valve. The valve opens when the patient inhales, passing the vaporized medication to the patient for inhalation. The dosage of vaporized medication is user controlled. The slit valve fails to retain bursts of vaporized medication from the cannister containing pressurized medication.
The U.S. Pat. No. 5,040,527, issued to Larson et al; U.S. Pat. No. 5,363,842, issued to Mishelevich et al; U.S. Pat. No. 5,415,161, issued to Ryder; and U.S. Pat. No. 5,743,252, issued to Rubsamen et al each teach the use of a replaceable cannister containing a pressurized aerosol inhalant, a vaporized medication, under high pressure. Upon release from the cannister, an high velocity burst of vaporized medication is entrapped in and fills a patient breathing cylinder and mouth piece through which the patient is breathing. The high velocity burst of medication from the pressurized cannister results in an excess portion of the drug being administered to the patient and depositing the excess portion in the patient""s mouth. The high velocity burst of medication from the pressurized cannister also results in a loss of medication through the openings in the breathing cylinder. U.S. Pat. No. 5,431,154, issued to Seigel et al also teaches the use of a replaceable, aerosol cannister of vaporized medication under pressure and further teaches limiting the pressure of the burst of high velocity spray of medication after the burst is released from the cannister.
The U.S. Pat. No. 5,522,380, issued to Dwork and U.S. Pat. No. 5,839,430, issued to Cama each teach a combination peak flow meter and metered dose inhaler. However, each patent teaches the use of a pressurized cannister which contains vaporized medication under high pressure. In the case of Cama, the complete cannister of pressurized medication is inserted into the breathing chamber of the device so that bursts of medication are emitted from the cannister directly into the mouth piece of the device and therefore into the mouth of the patient. In the case of Dwork, in the output nozzle of the high pressure cannister is inserted directly into the breathing chamber of the device. In each case, the high velocity burst of medication into the breathing chamber deposits an huge amount of medication into the mouth of the patient and medication is lost out the vent hole in the breathing chamber. Dosage from the cannister, in bursts of high velocity medication, is patient controlled. By depositing high velocity bursts of medication directly into the chamber or cylinder of the peak flow meter, medication is lost up the calibrated cylinder of the peak flow meter and inaccuracy in the peak flow meter is amplified by getting the movable diaphragm, in the case of Cama, and a ball float in the case of Dwork, wet from the vaporized medications burst into the unit.
The present invention provides a peak flow meter and nebulizer, combined to provide patients and clinicians with an improved medical device which delivers vaporized medication to a patient, for inhalation, and monitors the patient""s air intake during the same respiratory cycle. Peak flow rate meters may be used to determine the severity of air flow obstruction caused by the swelling of tissue in the respiratory system. Monitoring the peak flow rate directly after medication for relief of air flow obstruction has been taken, can determine the immediate effectiveness of the medication.
A peak flow meter consists of an open ended chamber for capturing exhaled breath, in an expandable space, for measuring the flow rate of breath expelled from a patient. The exhaled breath-capturing chamber or breathalizer chamber is an open ended chamber, with a mouth piece at the other end. The chamber houses a lightly biased, movable baffle or diaphragm which moves within the chamber in accordance with the flow rate of breath exhaled into the chamber. A graduated scale, marked along the cylinder is used for measuring the breath exhaled into the cylinder. The nebulizer is a medication delivery device or system which delivers medication, in vaporized or mist form, for inhalation by a patient. The nebulizer includes a vapor or mist capturing chamber or breathalizer chamber, which is open at one end, with a mouth piece at the other end. The vaporized medication capturing chamber or breathalizer chamber permits the patient to inhale, unobstructedly, the vaporized medication delivered to the breathalizer chamber, along with air.
From one aspect of the invention, there is provided a peak flow meter and a nebulizer, connected so as to use a common breathalizer chamber. The peak flow meter comprises an opened cylinder with a mouth piece at the other end. A lightly biased baffle or diaphragm is supported in the breathalizer chamber for capturing exhaled breath and defining a space in the breathalizer chamber, which is a function of the flow rate of the breath exhaled from a patient through the mouth piece. The nebulizer is a vapor or mist generating and delivery device or system which converts a liquid medication, for example, into a mist or vaporized medication by bubbling air or oxygen, under low pressure, through the liquid medication. The vaporized medication is delivered to a patient for inhalation, along with air or oxygen. In accordance with the present invention, vaporized medication of a nebulizer is delivered to the common breathalizer chamber, for inhalation, with air or oxygen. A one way valve is provided between the common breathalizer chamber and the vaporization unit of the nebulizer. Connection by the medication vaporization unit of the nebulizer to the breathalizer chamber is at a point between the normal position of the lightly biased diaphragm and the mouth piece at the end of the breathalizer chamber. A one way valve between the vaporization unit and the common chamber maintains the integrity of the measurement of the peak flow meter and permits delivery of the vaporized medication. The one way valve may be an automatic leaf valve or ball check valve or may be a manually operated, spring loaded sliding plate valve or a rotatable ball channel valve.
From another aspect of the invention, a peak flow meter and a nebulizer are combined with individual corresponding units in parallel relationship where the corresponding units have common ends and a valve for connecting a common mouth piece to the respective corresponding units. A single cylinder or elongated chamber, with a mouth piece at one end and an open end at the other end, is divided into two, essentially parallel chambers by a common wall. One chamber serves as a breathalizer chamber for the peak flow meter and the other chamber serves as a breathalizer chamber for the nebulizer system. The common mouth piece at one end of the single cylinder includes a valve that shuts off one breathalizer chamber from the common mouth piece and opens the other breathalizer chamber to the common mouth piece. The valve may be a manually operable valve, such as a rotatable half open disk valve or an automatic valve such as a double leaf one way valve, with one leaf of the double leaf valve opening in response to exhalation through the mouth piece and closing in response to inhalation through the mouth piece while the second leaf of the double leaf valve closes in response to exhalation through the mouth piece and opens in response to inhalation through the mouth piece.
From a further aspect the invention provides a spirometer or peak flow meter combined with a nebulizer which share common components. Each device utilizes common components individually, to the exclusion of the other, on a time share basis. The time shared is the time of the respiratory cycle of a patient.